Valorisation of organic wastes through black soldier fly (Hermetia illucens) Larvae: Impacts on Growth, nutritional Composition, and bioconversion efficiency

• In Nepal, urban organic wastes were successfully valorised by black soldier fly (BSF) larvae. • Larval growth and waste reduction (>70 %) were highest in kitchen and restaurant wastes. • Low bioconversion efficiency and significant larval mortality (76%) were observed in butcher chicken waste. • Larvae with the highest protein content (37% DM) have grown from restaurant waste. • In developing nations, BSF technology supports decentralized waste management and the circular bio-economy. Organic waste accumulation poses a significant environmental challenge, necessitating effective waste management strategies. The black soldier fly serves as a beneficial insect, aiding in waste reduction and animal feed production, while its frass contributes to sustainable soil improvement. Therefore, this study is aimed to investigate the bioconversion efficiency, growth performance, longevity, waste reduction, and nutritional composition of Hermetia illucens (Black soldier fly; BSF) larvae reared on five different urban organic wastes: restaurant waste, vegetable waste, fruit waste, kitchen waste, and butchery chicken waste following completely randomized design (CRD) with five urban waste treatment and four replications. The results revealed the highest larval growth rate and bioconversion found on restaurant waste 12.02 ± 0.47 mg/day and 6.97 ± 0.15 % respectively. Larva reared on butchery chicken waste showed highest larval mortality (76.02 ± 0.42 %) and life cycle duration (57 days). Also, the highest decomposition rate of waste was found on kitchen waste (0.73 ± 0.02) and fruit waste (0.72 ± 0.009). The highest waste reduction rate was found on kitchen waste (73.66 ± 2.70 %) and restaurant waste (62 ± 0.94 %). Larvae reared on restaurant waste exhibited highest crude protein content (37 ± 0.44 %DM), whereas highest crude fat was found on larva reared on butchery chicken waste (47.4 ± 0.64 %DM). The study highlights how BSF can efficiently decrease waste quantities and transform nutrient-balanced urban organic wastes into high-value biomass. The most promising substrates for large-scale BSF rearing and circular bio economy applications in developing nations like Nepal were found to be kitchen and restaurant wastes.